1. Field of the Invention
The invention relates generally to testing electronic components and, more specifically, to distinguishing one type of component from another type of component packaged in the same style of package.
2. Description of Related Art
Electronic components, or "chips," generally comprise a small piece of semiconducting material (usually silicon) on which an integrated circuit is embedded. The semiconducting material is packaged within an encapsulation, such as a plastic case, with a plurality of terminals, also referred to as pins, legs or leads, extending from the component case. Different types of chips include microprocessor chips, which contain an entire processing unit, and memory chips, which store data.
Common component package styles include dual in-line packages (DIP), which are the traditional bug-like chips that have anywhere from 8 to over 40 terminals configured to extend through holes in a printed circuit board, evenly divided in two rows. Pin-grid arrays (PGA) are square chips in which the pins are arranged in concentric squares, and single in-line packages (SIP) are chips that have just one row of legs in a straight line like a comb. In addition to these types of chips, there are also single in-line memory modules (SIMM) and dual in-line memory modules (DIMM), which consist of several memory chips packaged as a single unit. Other types of chip package styles include small outline packages (SOP), which include terminals configured for surface mounting, wherein the chip terminals are connected to the surface of a printed circuit board, rather than extending through a hole in the circuit board. Variations on SOPs include shrink small outline packages (SSOP), very small outline packages (VSOP), thin small outline packages (TSOP) and thin shrink small outline packages (TSSOP).
Electronic components, such as memory chips, are customarily manufactured in multiple configurations. For example, a single type of memory chip may include variations which store different amounts of data, or there may be various ways to arrange the data stored within the memory chip. These various configurations, however, may be packaged in identical chip package styles, making the various configurations indistinguishable to one simply looking at the configuration, size or shape of the chip.
In most manufacturing processes, including manufacturing electronic components such as chips, a series of checks and inspections are typically employed to insure that quality standards are met. Often, these quality assurance tests are simply "pass-fail" checks, though this is not necessarily the most practical manufacturing practice. While manufacturers may prefer to only ship products conforming to the highest standards, this is not always economically feasible, since different applications for manufactured items require different quality or reliability levels. Since, the manufacturing cost generally increases as the quality level increases, manufacturers need to use as many products produced as possible.
For example, computer memory devices are manufactured to store a predetermined amount of data. Computer random access memory (RAM), or main memory, can be thought as an array of boxes, each of which can hold a single byte of information. A memory device that stores one megabyte (meg) of memory, therefore, can hold about one million bytes (or characters) of information. There are several types of computer memory devices, including static RAM (SRAM), dynamic RAM (DRAM) and synchronous DRAM (SDRAM). Thus, a 16 meg DRAM is supposed to hold approximately 16 megs of data.
If, during quality assurance testing, a 16 meg DRAM is found to have some defective arrays, such that the 16 meg DRAM only is capable of storing 15 megs of data, it typically would fail the quality assurance test and be scrapped. A scrapped DRAM may also be referred to as a "partial" or a "partial DRAM". If components such as the partial DRAMs are retested and the bad arrays are identified, there are many applications which can use these partials, preventing waste and reducing manufacturing costs. Some manufacturers have implemented "component recovery" programs to make use of subperforming components such as these partial DRAM chips. Other companies specialize in component recovery, buying products which may have been rejected during the initial manufacturing process then sorting, retesting, and grading the products for use in their own products where appropriate, or reselling them for use in suitable applications.
A significant problem with current component recovery programs occurs when the component fails the original quality assurance test, and the initial manufacturing process for the failing component halts. Because the process halts, these parts are not marked to identify the component type on the component package. Many different types or configurations of electronic components may be contained in packages that look identical. Absent an indication of the component type on the package, it is impossible to identify the component visually. Moreover, even if the components are marked, a component recovery company that purchases graded components or partials may demark the component so that it may be remarked with the recovery company's identifier. This demarking process must occur prior to component testing to insure that the demarking process did not damage the component.
Thus, a need exists for a system and method for distinguishing one component type from another component type that is contained in the same package style.